Swimming pool????

Been flying my ass off lately, but got about an hour to dink around at the welding table today. On a recent trip, I picked up a pound of 1/16" and .045 316l filler wire. The .045 is way too small and the 1/16" feels right when I ditched the 3/32" tungsten for a 1/16". Anyhow, while putzing around, I had two pieces tacked together and let it cool. I tried to break it free and couldn't do it without a hammer. This got me thinking. Why am I seeking 100% penetration for these welds? I'm choosing 1/8" SS for structural strength and integrity of the "box" and the welds main purpose is to basically seal in the water? I took two coupons and fusion welded the two together without filler running on pulse. Let it cool, flipped it over and ran the back side also. I understand fusion welding basically leaves a small concave surface due to pulling metal from both sides and you no longer have the original material thickness. But it didn't lose that much material! I showed the wife and asked if she was fine with seeing this in the finished surface under water. No complaints! I need to load this in the 20ton press and see what kind of torture it can tolerate. By comparison, if i mig these visible butt welds, I'll be grinding until the cows come home! A mig machine is going to make short work of non visible welds like angular reinforcements on the back, corners and etc, but the TIG machine might be the answer for a lot of this.... On pulse it's fast and the heat affected zone stays very small and wont screw the stainless in the process.

Take a peak at this sample. Picture doesn't really do this justice, It's pretty damn smooth and best part, NO WARPING!

Interesting read on this...https://weldingweb.com/showthread.php?17038-Autogeneous-TIG-pic&highlight=tig stainless

https://forum.millerwelds.com/forum/welding-discussions/19515-fusion-weld-stregenth-w-stainless

https://www.lincolnelectric.com/en-...heory/Pages/weld-fusion-weld-penetration.aspx

 

What if you had a 1/2" wide by 1/8" thick backing strip tack welded behind where the two sheets meet?. That would keep the sheets in perfect alignment, act as a heatsink and if you were gunning for a full depth weld it would help prevent burn-through.

 

Slick idea Mark. I'll give it a try. It would not need back purging that way too.

 

It'd be a standard bar size too, no need to muck around cutting strips unless it's cheaper to guillotine them.

 

Go ahead and try a 12" long test next. Then a 24". If you can keep them flat you're getting there.

Nothing wrong with no filler metal. And nothing wrong with no back weld.

 

I like the idea of strips on the back, but it will prevent me from welding the back seem completely... Unless I'm missing something? Now I could weld one side, add the strip over the joint and then flip and weld the front.... That what you were thinking Mark? I'm pretty fried at the moment. I think the heat is turning my brain to mush.

 

A backing strip is so you can run hot and burn through without making holes. May not be the best for warpage control.

 

Say you have two vertical sheets, with a horizontal weld joining them: a strip tacked to the back of the lower sheet before welding would let you push hard against the upper sheet and keep the two sheets aligned.
For the bottom of the pool, the strip would be tacked to one sheet only and the next sheet would rest on the strip. You could even stand on the sheet and the edges would still align for welding.

It's a sheet alignment aid for a lone welder working on his own.

 

Ahh, that makes sense now to me.

Fell down the YT rabbit hole tonight. WTF is this magic wand????

 

$30,000 and you're good to go!!

 

30k? Yeah that ain't happening. I took that coupon from above to total destruction last night. I bent it into a crescent shape (about 2inch diameter circle with no cracking across that weld. I then folded it in half to complete destruction. It took a lot of beating to get it to break and while that's a good thing, I didn't like the penetration inside I saw. Will need to tweak some welder settings for this method to be viable. Here is a look under a magnifier. The best penetration is in the center on the one side of the fusion joint.

 

When is the steel being delivered? I'm getting anxious to book the flights............

 

I heard Jason came up with a solution to make the pool from a single seamless sheet of metal using explosive forming into a concrete mold in situ .

 

Now that's a good idea Mark! This week I am meeting with some local tank builders to work out some welding questions. I also mailed some coupons and filler wire to 6th street fab (YT channel) He runs an invertig so this should be interesting to see that in the next week or two. The airplane is going down for heavy maintenance soon so that is going to put a huge hole in my calender. I think while that is happening should be a good time to iron out the plans for the city. That is the one thing I am dreading the most. You can assemble a POS junk kit and put a vinyl liner in it and no one bats an eye or asks for engineering drawings. I'm curious what the local building folks are going to say about this one. I can hear it now... "You need to hire an engineer" That's when this thing will turn into a "koi pond" faster than you can take your swimsuit off! People have a funny way of clamming up when you show them something they have never seen before. I think it's the fear of looking ignorant. Hopefully I won't get someone that's not afraid to think outside the box. When I fill it with water in the driveway free standing, that should be all the testing it needs. Try that with your gunite pool. HA!

 

You're craning it over full of water? I wanna come watch (Joke)

Seriously though that thing is going to flex no matter how rigid you make it, the lift itself could easily crack something. Can you get the welder to it in situ to repair a crack?

 

I expect some flexing and a possible leak or two, I am new to welding SS after all. So my plan is to sit this thing inside a concrete vault with 2 foot of spacing surrounding it on all four sides. This way if a leak develops on a wall, I can squeeze my skinny ass and welder onto the backside of the walls if need be. If the floor leaks, I'm just hooped and will only be able to weld inside the vessel. So no backfill. The tricky part I'm working on is how to dry in that area. That "ceiling" has to cover the hallways, remain dry and also span onto the edge of the vessel to create the deck. I'm thinking engineered composite decking with the strips in between the boards to dry it in. Glued in place, they could be removed if the sun destroys them. The composite decking world got royal screwed about 7-10 years ago with massive lawsuits. Word on the street is they have fixed the problems with uv degradation. I hope so! A prettier solution would be interlocking travertine squares, but the weight resting on the edge would be more than I want to deal with.

 

You've got an old British car, you must have gallons of 'bars leaks' on tap... I'm not helping am I.

I would think the tiny occasional pin hole would be a potential issue, tank welding they do hydro tests under moderate pressure.

I dealt with some polymer guys years ago (think 'beaker' the chemist in the muppet show and you'd be close) they developed some wood effect deck with a foam core, no idea where that ended up but it was clever at the time. I've dealt with UV in other plastics and it can be very cruel.

I'm sure you are going to iron these things out and the approach is great to follow.

 

You funny guy peedee... The old jag only leaks a bit of oil these days. At 5 feet deep, pressure is only around 15psi. I can fart with more pressure than that!
Wise old man taught me years ago, never trust a fart over 50! So I'm safe for now at 45.

The experts seem to think only 4psi is the best one can muster. http://www.kgbanswers.com/what-is-the-average-psi-of-a-human-fart/4511275

 

I'd run a Solidworks FEA on the effect of the fart but I can't find it listed under 'parameters'...........

Edit, found some numbers I could manually load : "there are about 9.6E+20 molecules in a fart. At an emission temperature of 310.15 K, the average molecule would have an energy of 6.4E-21 J. The thermal energy of a fart, then, is 6.2 Joules, which is about 34000 times greater than the kinetic energy.